Optical lens and backlight module incorporating the same

Abstract

An optical lens includes a first optical surface located at a bottom thereof, a third optical surface located at a top thereof and arranged oppositely to the first optical surface, and a second optical surface extending between the first optical surface and the third optical surface. The third optical surface is recessed downwardly towards the first optical surface. The light from the LED light source enters into the optical lens through the first optical surface, most of the entering light is directly refracted out of the optical lens through the second optical surface, and a part of the entering light that strikes the third optical surface is first reflected by the third optical surface towards the second optical surface via total internal reflection and then refracted out of the optical lens through the second optical surface. A backlight module incorporating the optical lens is also provided.

What is claimed is: 
     
       1. A backlight module comprising:
 an LED light source; and 
 an optical lens optically coupled to the LED light source for diverging light emitted therefrom, the optical lens comprising a first optical surface located at a bottom thereof, a third optical surface located at a top thereof and arranged oppositely to the first optical surface, and a second optical surface located at a lateral side thereof and extending between the first optical surface and the third optical surface; 
 wherein the third optical surface is recessed downwardly towards the first optical surface and surrounded by the second optical surface; 
 wherein the light emitted from the LED light source enters into the optical lens through the first optical surface, most of the entering light is directly refracted out of the optical lens through the second optical surface and at least a part of the entering light that strikes the third optical surface is first reflected by the third optical surface towards the second optical surface via total internal reflection and then refracted out of the optical lens through the second optical surface; and 
 wherein the first optical surface comprises a top wall and a cylindrical inner wall extending downwardly from the top wall, and the top wall and the cylindrical inner wall cooperatively form a receiving cavity for accommodating the LED light source, the LED light source is arranged under the receiving cavity and a top of the LED light source covers an opening of the receiving cavity. 
 
     
     
       2. The backlight module of  claim 1 , wherein the second optical surface comprises a first light exit surface and a second light exit surface connected to the first light exit surface, the second light exit surface is a cylindrical surface, and the first light exit surface is a convex curved surface having a radius slightly larger than that of the second light exit surface. 
     
     
       3. The backlight module of  claim 1 , wherein the LED light source comprises a substrate and a LED chip, the substrate defines a recess in a top side thereof corresponding to the receiving cavity for receiving the LED chip therein, and an inner diameter of the recess gradually decreases from the top to the bottom thereof. 
     
     
       4. The backlight module of  claim 3 , wherein the LED light source further comprises an encapsulating layer spaced from the LED chip and covering an opening of the recess, and the encapsulating layer has phosphor particles doped therein to convert a wavelength of the light from the LED chip. 
     
     
       5. The backlight module of  claim 2 , wherein a light spreading surface is recessed upwardly from the top wall of the first optical surface towards the third optical surface, and the light spreading surface is a conical surface having a gradually reduced inner diameter towards the third optical surface. 
     
     
       6. The backlight module of  claim 5 , wherein an apex of the light spreading surface is lower than an intersection of the second light exit surface and the first light exit surface. 
     
     
       7. The backlight module of  claim 2 , wherein the optical lens further comprises a bottom surface interconnecting the first optical surface and the first light exit surface of the second optical surface, wherein the receiving cavity is recessed upwardly from a central portion of the bottom surface towards the third optical surface. 
     
     
       8. The backlight module of  claim 2 , wherein the third optical surface is an inverted conical surface having a gradually reduced inner diameter towards the first optical surface. 
     
     
       9. The backlight module of  claim 8 , wherein a bottom of the third optical surface is higher than an intersection of the second light exit surface and the first light exit surface. 
     
     
       10. The backlight module of  claim 7 , wherein the optical lens further comprises a plurality of fixing pins extending downwardly from the bottom surface for firmly fixing the optical lens onto a target object, the fixing pins being placed at approximately equal intervals around an outer periphery of the bottom surface.